This invention relates to superconductor materials and more particularly to methods of making superconductor compositions having the formula YBa.sub.2 Cu.sub.3 O.sub.x.
The scientific literature has recently described many new compositions which display superconductivity at temperatures above the liquid nitrogen temperature. When such compositions are cooled to the liquid nitrogen temperature, they essentially display a zero resistance to electrical current and therefore offer the possibility of dramatic improvements in such apparatus as transmission lines and electromagnetic coils. One promising superconductive ceramic composition has the formula YBa.sub.2 Cu.sub.3 O.sub.x, where x may vary between 6.5 and 7.0, depending upon the processing procedure used for making the composition. Many workers have experimented with ways for formulating this composition, have assessed its characteristics, and have described in the scientific literature the results they have obtained; one example of such literature is the paper, "Synthesis, Characterization and Fabrication of High Temperature Superconducting Oxides," by E. C. Behrman et al., "Advanced Ceramics Materials," Vol. 2, No. 3B, Special Issue, 1987, p. 539.
While YBa.sub.2 Cu.sub.3 O.sub.x is commercially promising because it becomes superconductive at temperatures higher than the liquid nitrogen temperature, it is a rather porous ceramic material that is not easily worked. It has been recognized that if this composition could be made more dense (i.e., less porous), it would be mechanically stronger and have less propensity to fracture. Other advantages that would be obtained by increased densification would be increased chemical stability, increased current density, and increased reliability.